Crime scene search methods

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carried out by a single person involves the searcher walking in a circular fashion from the outer point of the crime scene towards the central point DO NOT START IN CENTRE AS EVIDENCE MAY BE DESTROYED

zone method

entire scene is divided into zones that are searched individually best for searching for a small object

strip method

area is divided into strips about 1 metre wide. the searcher examines each strip separately. best for outdoor area

grid searching

advance on the strip method searchers complete the strip method and double back across the area being searched

searching indoors

walls and ceilings should be examined beat to work from top downwards critical evidence may be found in the least obvious places

searching outdoors

similar to indoors, fingerprints found less frequently, almost all evidence will be on the ground.pay attention to fragile evidence as it may be destroyed. protect 2D or 3D impressions footprints. note any odours.

retrieving evidence

packaging must be new, before taking any item make a note of its position and appearance, each item should be properly packed and labelled

avoid contamination

avoid breakage, evaporation, accidental scratching or bending

blood, hair, fibres, soil

do not remove from clothes weapons etc before sending to lab

stains

stains on large objects may be cut out or removed using a swab

sources of contamination

contamination occurs when trace evidence transfers to or from the scene after crime and before forensic analysis

crime scene examiner

may transfer there own DNA hair or fibres to crime scene or evidence

primary transfer

direct contact between items from different aspects of the case or between victim and suspect after incident

secondary transfer

same person handling items from different aspects of the case

avoiding contamination

wear clean disposable over garments, gloves and masks, never talk over evidence, clean all examination surfaces, items packed sealed and labelled before removal from the crime scene and not reopened before examination different police should deal with different sides of the case, victims and suspects not be transported in the same car.

labelling items

each item should have a clear lable with this information police district concerned, nature of occurrence or crime, name of injured party, name of accused suspect, where and when item was found, identifying number, name of person who found the item, date

evidence containers

envelopes, screw cap glass vials, saleable plastic bags, air tight containers should not be used for bloodstained items as mould may grow paper bag is used instead, charred items of fire should be sealed in air tight containers to stop evaporation of petroleum residues